In hospitals and other institutions, it is commonplace to utilize compressed medical gas such as oxygen, nitrous oxide or air. This gas is often stored under high pressure in cylinders. Conventionally, the head of a compressed gas cylinder is connected to a unitary regulator-flow meter assembly. The regulator-flow meter assembly usually includes a main valve for closing off the flow of gas from the cylinder or opening the gas line to permit gas to flow from the cylinder to the regulator. When the main valve is open, gas flows from the regulator through the flow meter to a tube by means of which it is conveyed to the point of use.
The main valves of regulator-flow meter assemblies are normally provided with an upstanding flat stem which is rotated to open or close the valve. In addition, the usual regulator-flow meter assembly includes a yoke or handle in the form of a cylindrical rod mounted to extend transversely of a rotatable shaft. This yoke is turned to securely seat the assembly on the gas cylinder and provide a gas-tight seal.
In the past, nurses, orderlies, respiratory technicians, therapists and other operators of this type of equipment have been provided with elongated key members for opening and closing the main valve. These elongated key members are provided with elongated openings adapted to fit over the flat valve stem. On of these openings is aligned with the longitudinal axis of the key while the second opening is arranged at right angles to the axis of the stem.
Such prior art keys have been subject to a number of disadvantages, despite which the the basic design of the key has remained the same over a period of many years.
The first disadvantage of prior art keys is that users tend to insert the cylindrical yoke in one of the elongated openings so that the key can be used for turning the regulator yoke. This causes two problems. In the first place, the elongated openings in the key are deformed after a period of use so that they no longer properly engage the stem of the main valve, but rather slip relative to the stem, rendering the key useless for opening and closing the main cylinder valve. In addition, the engagement of the elongated slot with the cylindrical handle results in an appreciable bending torque being applied to the yoke with the result that the yokes, on occasion, have become badly bent or the seals compressed by turning the yoke have been damaged.
Another disadvantage of prior keys is that they are relatively large and are normally carried loose in the operator's pocket, with the result that the keys are frequently misplaced or lost.